1. Field of the Invention
The present invention is generally directed to an electronic navigational device employing a receiver for receiving GPS satellite signals. More particularly, the present invention is directed to an electronic navigation device and a method for selectively displaying the names of thoroughfares stored in a memory device.
2. Description of the Related Art
Electronic navigation devices employing GPS receivers have become increasingly popular in recent years. The device is utilized in an electronic navigation system which permits a user of the system to determine his or her position with respect to the earth. Such navigation devices are extremely useful in navigational vehicles of all types, including aircraft, marine craft, and land vehicles. Additionally, the device is useful for tracking purposes, and hand held versions are popular with hikers and campers. Very generally, conventional electronic navigation devices employ a receiver which detects signals from a number of satellites orbiting the earth. The processor within the navigation device computes the location of the device, based upon data received from the received satellite signals, after a sufficient number of GPS satellite signals have been acquired. Particularly, once a sufficient number of GPS satellite signals are acquired, the device is able to calculate its position with respect to the various satellites. Thus, an electronic navigation device employing a GPS receiver has the ability to accurately compute the position of the device in real time, even as the device moves. Additionally, the device is able to calculate the velocity and direction in which the device is moving in three dimensions.
U.S. Pat. No. 5,323,164 to Endo teaches a satellite radio wave capturing method for global positioning system receiver. U.S. Pat. No. 5,225,842 to Brown, et al. teaches a vehicle tracking system employing global position satellites. Each of these patents is incorporated herein by reference.
Users of navigation equipment seek intuitive representations of navigation information which are direct and simple to interpret. Particularly, the ability of a navigation device to present navigation information in a manner that is simple to interpret is particularly important to individuals navigating a land vehicle, since the operator of the vehicle does not want to have to spend significant time interpreting displayed navigation data.
Conventional navigational devices have electronic maps stored in memory. Particularly, data indicative of geography and thoroughfares are stored in memory. One such conventional navigation device are used in combination with a vehicle, such as an automobile, the navigation device calculates its location and provides an icon on the display screen, relative to displayed electronic map, to indicate to the operator of the vehicle the position and movement of the vehicle relative to surrounding geography. Typically, the electronic maps are displayed two dimensionally, although the electronic map data may also be transformed to a perspective view.
In conventional GPS navigation devices, each thoroughfare has an associated name stored in memory. Thus, upon display of a particular thoroughfare on the display of the navigation device, the name of that thoroughfare can also be displayed to indicate to the user the identity of the thoroughfare being displayed. As will be appreciated, in heavily populated areas, such as cities, there are a great number of thoroughfares in close proximity to each other. This presents a problem in displaying the names of each thoroughfare, due to the fact that the display screens on conventional navigational devices are not large enough to adequately show all of the names of closely related thoroughfares. More specifically, when thoroughfares are arranged in a grid pattern, such as city blocks which are often arranged, the names of streets oriented in one direction often overlap with the names of streets oriented in another direction on the display of the navigation device. In such a case, the displayed information is obviously not at all intuitive and, in fact, presents overlapping text which is extremely difficult, or impossible, to read. In response to this problem, methods have been implemented to eliminate the names of some of the roads for display of the cartographic information on the navigation device, so as to prevent the overlapping of names. While a variety of approaches are taken, these approaches result in randomly named streets appearing on the display, while the names of other streets or roads do not appear.
Accordingly, the need exists for a navigation device and method for displaying the names of thoroughfares on a navigation device which are most likely to be of interest to the navigator of a land vehicle. The present invention fulfills this need, and other needs, and overcomes the drawbacks of the prior art.